Search results for "trifluoromethyl"

Deformation of sulfur hexafluoride and floppiness of trifluoromethyl sulfur pentafluoride

2006

International audience; With recent advances in space exploration and atmospheric chemistry there is an increased need for more spectroscopic tools to allow the of study complex species. One such tool is the theory of frame transformation of coupled rotor systems. In this article, the theory of frame transformation along with the concept of rotational energy surface is used to study the symmetry that occurs in trifluoromethyl sulfur pentafluoride due to the internal rotation of the CF3 radical and, more generally, to the extent of floppiness of SF5CF3. Other lower symmetries when a CF4 molecule is stuck on the various symmetry axes of an SF6 molecule are also discussed.

Diphenylsulfone-based hosts for electroluminescent devices: Effect of donor substituents

2020

DG acknowledges to the ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/177. This work was supported by the project of scientific co-operation program between Latvia, Lithuania and Taiwan ?Polymeric Emitters with Controllable Thermally Activated Delayed Fluorescence for Solution-processable OLEDs? (grant No. S-LLT-19-4). Support of the Lithuanian Academy of Sciences is gratefully acknowledged; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

Synthesis and antiproliferative activities of two new analogs of tetrazepinones

Based on the encouraging results, we report the multistep synthesis and the biologicalo results of two new analogs of tetrazepinones: the 3,5-dimethyl-6-phenyl-8-(trifluoromethyl-5,6-dihydropyrazo1o[3-4-f]1,2,35)tetrazepin-4(3H)-one and the 3-(2-chloroethyl)-5-methyl-6-phenyl-8-(trifluoromethyl-5,6-dihydropyrazo1o[3-4-f]1,2,35)tetrazepin-4(3H)-one. Both compounds showed a pro-apoptotic activity against HL60 and K562 resistant cell lines. Flow cytometry studies carried out 0n K562 cells allowed to establish that the methyl derivative induces G0-G1, phase arrest followed by apoptosis, whereas the chloroethyl derivative is a not phase-specific agent.

Catalytic Enantioselective Conjugate Alkynylation of β-Aryl-β-trifluoromethyl Enones Constructing Propargylic All-Carbon Quaternary Stereogenic Cente…

2016

The enantioselective conjugate alkynylation of β-aryl-β-trifluoromethyl enones has been carried out using terminal alkynes and diethylzinc in the presence of 3,3'-bis(perfluorophenyl)BINOL as the chiral ligand to give the corresponding ketones bearing a trifluoromethylated propargylic quaternary stereocenter with fair to good enantioselectivities. Enones bearing a bulky 2-naphthyl attached to the carbonyl group provided the best enantioselectivities. The synthetic applicability of the resulting products has been demonstrated with their iodocyclization to form 4H-pyrans.

Enantioselective Synthesis of 5-Trifluoromethyl-2-oxazolines under Dual Silver/Organocatalysis.

2019

[EN] The first enantioselective formal [3 + 2] cycloaddition between ¿-isocyanoesters and trifluoromethylketones to give 5-trifluoromethyl-2-oxazolines bearing two contiguous stereogenic centers, one of them being a quaternary stereocenter substituted with a CF3 group, has been developed. The reaction is based upon a multicatalytic approach that combines a bifunctional Brønsted base-squaramide organocatalyst and Ag+ as Lewis acid. The reaction could be achieved with a range of aryl and heteroaryl trifluoromethyl ketones, and the resulting oxazolines were obtained with good to excellent diastereo- and enantioselectivity.

Mg/BOX complexes as efficient catalysts for the enantioselective Michael addition of malonates to β-trifluoromethyl-α,β-unsaturated ketones and their…

2021

Abstract Magnesium (II)-BOX complexes catalyze the enantioselective Michael addition of malonates to β-trifluoromethyl enones and their N-sulfonyl imines to give ketones or (E)-enamines bearing a trifluoromethylated stereogenic center, respectively, with good yields and high enantiomeric excesses. Magnesium complexes proved to be more active and stereoselective than zinc and copper analogues in these reactions.

Copper-catalysed enantioselective Michael addition of malonic esters to β-trifluoromethyl-α,β-unsaturated imines

2017

[EN] Copper triflate-BOX complexes catalyse the enantioselective conjugate addition of methyl malonate to beta-trifluoromethyl-alpha,beta-unsaturated imines to give the corresponding enamines bearing a trifluoromethylated stereogenic centre with good yields, and diastereo- and enantioselectivities. The usefulness of the method has been shown with the synthesis of optically active beta-trifluoromethyl delta-amino esters and optically active trifluoromethyl piperidones.

Catalytic Enantioselective Conjugate Alkynylation of α,β-Unsaturated 1,1,1-Trifluoromethyl Ketones with Terminal Alkynes.

2016

The first catalytic enantioselective conjugate alkynylation of α,β-unsaturated 1,1,1-trifluoromethyl ketones has been carried out. Terminal alkynes and 1,3-diynes were treated with trifluoromethyl ketones in the presence of a low catalytic load of a CuI-MeOBIPHEP complex (2.5 mol %) and triethylamine (10 mol %) to give the corresponding trifluoromethyl ketones bearing a propargylic stereogenic center at the β position with good yields and excellent enantiomeric excesses in most of the cases. No 1,2-addition products were formed under the reaction conditions. The procedure showed broad substrate scope for alkyne, diyne, and enone. A rationale for the observed stereochemistry has been provide…

CF3: An Electron-Withdrawing Substituent for Aromatic Anion Acceptors? “Side-On” versus “On-Top” Binding of Halides

2016

The ability of multiple CF3 -substituted arenes to act as acceptors for anions is investigated. The results of quantum-chemical calculations show that a high degree of trifluoromethyl substitution at the aromatic ring results in a positive quadrupole moment. However, depending on the polarizability of the anion and on the substitution at the arene, three different modes of interaction, namely Meisenheimer complex, side-on hydrogen bonding, or anion-π interaction, can occur. Experimentally, the side-on as well as a η(2) -type π-complex are observed in the crystal, whereas in solution only side-on binding is found.

Halogen‐Imparted Reactivity in Lithium Carbenoid Mediated Homologations of Imine Surrogates: Direct Assembly of bis‐Trifluoromethyl‐β‐Diketiminates a…

2020

The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation-metalation-acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β-diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the struct…